Priority to German Patent Application No. 102 22 225.8, filed May 16, 2002 and hereby incorporated by reference herein, is claimed.
The present invention relates to a cylinder covering having a lateral edge reinforcement, which is received partially overlapping on the cylinder covering, the cylinder covering having an upper side as the printing side. Furthermore, the present invention relates to a method of receiving a cylinder covering, which is provided on at least one first lateral edge with a lateral edge reinforcement, on a cylinder in a printing press, the cylinder having a narrow cylinder channel and at least one clamping device having a holding slot for the cylinder covering.
Cylinder coverings, such as rubber printing blankets, printing forms, plates having special surface properties, or the like, have been used in printing technology for a considerable length of time. While sleeve-shaped cylinder coverings are pulled over the cylinder essentially in the direction along the cylinder axis, flat cylinder coverings are spread curved over at least a part of the surface of the receiving cylinder and attached using one or more clamping devices, which exert forces in the tangential and radial directions of the surface on the part of the cylinder covering spread over the cylinder surface. In order to be able to use the largest possible surface for a given radius and given height of the cylinder, it is advantageous to position the clamping device(s) in the interior space of the cylinder and feed the edges of the cylinder covering through a cylinder channel, which is as small or narrow as possible and runs essentially parallel to the cylinder axis, to the clamping devices for attachment. An attachment element of the species described is disclosed, for example, in U.S. Pat. No. 4,648,318. Cylinders of this type are also referred to as mini-gap cylinders.
Typical, commonly used flat cylinder coverings have a layered construction, one side, the upper side, being referred to as the printing side. The cylinder covering is received on a cylinder in a printing press or a machine which processes materials to be printed in such a way that the upper side lies outwardly.
A cylinder covering in the form of a rubber printing blanket is described in European Patent Application No. 1 072 434 A1, for example. The rubber printing blanket has at least one elastomer layer as the printing side, a compressible layer, and a reinforcement layer. In order to allow the lateral edges of the rubber printing blanket to be received in a clamping device of a mini-gap cylinder, a cylinder having a narrow cylinder channel, the thickness of the rubber printing blanket is implemented as tapered on the sides of the relevant lateral edges in comparison to its thickness at a point which is located over the surface of the cylinder after the rubber printing blanket is spread out. A lateral edge to be received may be provided with a lateral edge reinforcement for stiffening.
A further, multilayered rubber printing blanket is known from U.S. Pat. No. 5,934,194. A lateral edge reinforcement for stiffening is attached on the lower side, the side facing away from the printing side, of the rubber printing blanket, partially overlapping with the rubber printing blanket.
A rubber printing blanket having a lateral edge reinforcement for stiffening, which encloses the rubber printing blanket partially overlapping both its upper side and its lower side, is disclosed in U.S. Pat. No. 3,489,085. The lateral edge reinforcement is considerably thicker than the rubber printing blanket. For attachment, the lateral edge reinforcement is received in an anchoring element. On the part not overlapping with the rubber printing blanket, the contour of the lateral edge reinforcement has a concave recess having a curved shape. The purpose of this recess is to provide a clearance to an edge of the anchoring element when the lateral edge reinforcement is inserted therein.
Inserting the lateral edges of a cylinder covering through a narrow cylinder channel into a clamping device having a holding slot in the interior space of the cylinder represents a difficulty which is not to be underestimated and an often time-consuming activity. To equip the cylinder, one lateral edge having a lateral edge reinforcement must be inserted through the cylinder channel into the interior space of the cylinder and then into the holding slot of the clamping device. The holding slot is typically essentially exactly as wide as the lateral edge reinforcement to be received, whether this reinforcement is attached only on the lower side of the cylinder covering or enclosing both the upper side and the lower side of the cylinder covering. Even slight tilting hinders the manipulation of the cylinder covering.
If a lateral edge reinforcement which encloses the upper side and the lower side is provided, a tool, whose end may be supported on a lateral edge of the lateral edge reinforcement, may also advantageously be used for pushing in the lateral edge reinforcement, since the enclosing lateral edge reinforcement is significantly wider than the cylinder covering. Since the lateral edge of an enclosing lateral edge reinforcement overlaps with the cylinder covering in this case, however, there is the danger of damage to the cylinder covering.
An object of the present invention is to make the manipulation of a cylinder covering during its attachment to a cylinder in a printing press easier.
According to the present invention, a cylinder covering having an upper side as a printing side has a lateral edge reinforcement, which is received partially overlapping on the cylinder covering. On the part not overlapping with the cylinder covering, the lateral edge reinforcement has at least one projection having a projection terminus on a lateral surface, which faces toward the upper side of the cylinder covering, of the lateral edge reinforcement, the perpendicular from the projection terminus to the plane of the overlapping part of the cylinder covering running at least partially outside or precisely on the contour of the lateral reinforcement. According to this representation, a positional plane of the lateral edge reinforcement attached to the cylinder covering, in particular a tangential plane on the lower side or upper side of the cylinder covering on the lateral edge provided with the lateral edge reinforcement, for example, is understood as the plane of the overlapping part of the cylinder covering.
In other words, according to the present invention the lateral edge reinforcement has, on its part which does not overlap the cylinder covering, a structure which is convex in relation to the part overlapping with the cylinder covering. This convex structurexe2x80x94having a partially non-convex, i.e., partially concave or partially straight contourxe2x80x94forms a projection which extends up to a projection terminus. The point of the contour which has an extreme position in relation to the projection is referred to as the projection terminus.
The projection advantageously forms a structure on the lateral surface of the lateral edge reinforcement on which a tool may be supported, in particular during the manipulation for receiving the cylinder covering on a cylinder in a printing press.
In a preferred embodiment, the cylinder covering is a rubber printing blanket. The projection may advantageously be implemented as hooked.
In an advantageous embodiment, the contour of the lateral edge reinforcement of the cylinder covering runs at least partially curved from the projection terminus in the direction toward the cylinder covering. In particular, the contour of the lateral edge reinforcement of the cylinder covering may have a concave shape from the projection terminus in the direction toward the cylinder covering. The concave shape may be uniform, progressive, or degressive. In a preferred embodiment, the projection is formed by a part of the lateral edge reinforcement which is curved in the direction of the upper side of the cylinder covering. The projection terminus may correspond to a point on a lateral edge of the lateral edge reinforcement of the cylinder covering.
In the method according to the present invention of receiving a cylinder covering, which is provided on at least one first lateral edge with a lateral edge reinforcement, on a cylinder in a printing press, the cylinder having a narrow cylinder channel and at least one clamping device having a holding slot for the cylinder covering, the lateral edge reinforcement on the first lateral edge of the cylinder covering is first inserted through the cylinder channel into the interior space of the cylinder. A part of the lateral edge reinforcement is then inserted into the holding slot of the clamping device. In order to push the lateral edge reinforcement into the holding slot, a tool is used. In this case, the tool is supported on a part of the lateral edge reinforcement which does not overlap with the cylinder covering. In particular, the tool may be supported on a projection on a lateral surface of the lateral edge reinforcement which faces toward the upper side of the cylinder covering.
A corresponding method may be used for a second lateral edge having a lateral edge reinforcement. In particular, the cylinder covering may be a cylinder covering according to the present invention, as is disclosed in the present description.
It is especially advantageous if the tool has an elastic shape or is flexible, since a clamping device is frequently positioned below the cylinder surface, but not on a direct radial path along the azimuth of the cylinder channel viewed outward from the cylinder axis. The tool may be curved in the interior space of the cylinder covering as it is supported on the lateral edge reinforcement while the lateral edge reinforcement is pushed into the holding slot.
The method according to the present invention is especially advantageously usable for cylinders which are received in a printing unit of a web-fed rotary press. In a refinement for clamping devices having clamping shafts, in the method according to the present invention, the cylinder covering is also clamped around the circumference of the cylinder by rotating the clamping shaft in a clamping direction.